Computer/integrating Systems: Other Chevrolet Silverado 1500

Body Control Module (BCM) - C1

Body Control Module (BCM) - C1 Connector Part Information 12177194 6-Way F Metri-Pack 150 Series (NA) Pin Wire Color Circuit No. Function A RD 2353 Instrument Panel Lamps Dimming Supply Voltage B PU/WH 1382 LED Dimming Signal C OG 4040 Battery Positive Voltage D OG 1732 Inadvertent Power Courtesy Lamps Supply Voltage E BN/WH 230 Instrument Panel Lamps Dimming Control F OG 2240 Battery Positive Voltage

Body Control Module (BCM) - C2

Body Control Module (BCM) - C2 Connector Part Information 12110088 24-Way F Micro-Pack 100 Series (GY) Pin Wire Color Circuit No. Function A1 - - Not Used A2 D-BU 1796 Steering Wheel Radio Controls Supply Voltage (UK3) A3 D-BU 245 Passenger Door Lock Switch Unlock Control - Base TN/BK 254 Rear Door Unlock Relay Control - Uplevel A4 PK/WH 1970 Headlamp Low Beam Relay Control A5 D-GN/WH 1317 Fog Lamp Relay Control A6 L-BU 244 Passenger Door Lock Switch Lock Control - Base GY/BK 255 Rear Door Lock Relay Control - Uplevel A7 - - Not Used - Uplevel L-GN 1391 Driver Door Unlock Relay Control - Base A8 WH 193 Rear Defog Relay Control A9-A10 - - Not Used A11 RD/WH 812 12-Volt Reference A12 OG 1140 Battery Positive Voltage B1 BK/WH 1969 Headlamp High Beam Relay Control B2 WH 1080 Park Lamp Relay Control B3 D-BU 1353 RAP Supply Voltage B4 L-GN/BK 592 DRL Relay Control B5 PU 359 DRL Off Indicator Control B6 BK/WH 1851 Ground B7 BK 1835 Security System Sensor Low Reference B8 PK 1348 Headlamp On Indicator Control B9 BK 28 Horn Relay Control B10 - - Not Used B11 GY 1056 Dimming Potentiometer 5-Volt Reference B12 L-GN 1037 BCM Class 2 Serial Data

Body Control Module (BCM) - C3

Body Control Module (BCM) - C3 Connector Part Information 12160778 24-Way F Micro-Pack 100 Series (BN) Pin Wire Color Circuit No. Function A1-A3 - - Not Used A4 WH 278 Ambient Light Sensor Signal A5 - - Not Used - w/o CJ2 GY 1548 Passenger Sunload Sensor Signal - CJ2 A6 YE 1836 Security System Sensor Signal A7 - - Not Used - Base L-GN 1011 Remote Radio Control Signal (UK3) A8 D-GN 588 DRL Switch Signal A9 OG 192 Front Fog Lamp Switch Signal A10 - - Not Used A11 PU 328 Interior Lamp Defeat Switch Signal A12 - - Not Used B1 - - Not Used B2 GY/BK 308 Park Lamp Switch Signal B3-B4 - - Not Used B5 - - Not Used - w/o CJ2 L-BU/BK 590 Driver Sunload Sensor Signal - CJ2 B6 BK/WH 1851 Ground B7 - - Not Used L-BU 1059 Steering Wheel Position Sensor Signal - NYS B8 OG/BK 2090 Dimming Switch Signal B9 L-GN 11 Headlamp Dimmer Switch Signal B10 - - Not Used B11 L-BU 553 Tow/Haul Switch Signal B12 - - Not Used

Body Control Module (BCM) - C4

Body Control Module (BCM) - C4 Connector Part Information 12110206 24-Way F Micro-Pack 100 Series (L-BU) Pin Wire Color Circuit No. Function A1 L-GN 80 Key In Ignition Switch Signal A2 YE 307 Headlamp Switch Flash to Pass Signal A3 WH 530 Off/Run/Crank Voltage A4 PK 39 Ignition 1 Voltage A5 - - Not Used - Uplevel BK/WH 746 Right Front Door Ajar Switch Signal - Base A6 D-BU/WH 149 Cargo Lamp Low Control A7 L-BU 1134 Park Brake Switch Signal A8 GY 1524 Backup Lamp Signal A9-A11 - - Not Used A12 WH 103 Headlamp Switch Headlamps On Signal B1-B2 - - Not Used B3 YE 43 Accessory Voltage B4 - - Not Used - Uplevel GY/BK 745 Left Front Door Ajar Switch Signal - Base B5 - - Not Used - Uplevel L-BU 195 Door Lock Control - Base B6 GY/BK 2226 Instrument Panel Lamps Dimmer Switch Low Reference B7 BK 279 Ambient Light Sensor Low Reference B8 - - Not Used B9 D-BU/WH 1495 Courtesy Lamps On Signal B10 - - Not Used - Uplevel WH 194 Door Unlock Control - Base B11-B12 - - Not Used

Body Control Module (BCM) - C5

Body Control Module (BCM) - C5 Connector Part Information 12177195 6-Way F Metri-Pack 150 Series (BK) Pin Wire Color Circuit No. Function A-C - - Not Used D OG 2140 Battery Positive Voltage E GY/BK 690 Courtesy Lamp Control F L-GN 24 Backup Lamp Supply Voltage

Body Control Module (BCM) - C6

Body Control Module (BCM) - C6 Connector Part Information 12191375 16-Way F Micro-Pack 100 Series (PU) Pin Wire Color Circuit No. Function A1 - - Not Used A2 L-GN/BK 748 Right Rear Door Ajar Switch Signal A3 L-BU/BK 747 Left Rear Door Ajar Switch Signal A4 - - Not Used A5 - - Not Used - Base L-BU 2265 Power Window Lockout Left Rear Control - Uplevel A6 - - Not Used - Base L-GN 2266 Power Window Lockout Right Rear Control - Uplevel A7 - - Not Used - Base GY/BK 1186 Power Window Relay Right Rear Up Control - Uplevel A8 - - Not Used - Base D-GN 1188 Power Window Relay Right Rear Down Control - Uplevel B1-B6 - - Not Used B7 - - Not Used - Base YE 1187 Power Window Relay Left Rear Down Control - Uplevel B8 - - Not Used - Base WH 1185 Power Window Relay Left Rear Up Control - Uplevel

Data Link Connector (DLC)

Data Link Connector (DLC) Connector Part Information 12110250 16-Way F Metri-Pack 150 Series (BK) Pin Wire Color Circuit No. Function 1 - - Not Used 2 PU 1132 DLC Class 2 Serial Data 3 - - Not Used 4 BK 1050 Ground 5 BK/WH 1851 Ground 6 - - Not Used - w/o HP2 TN/WH 2500 High Speed GM LAN Serial Data (+) - HP2 7-13 - - Not Used 14 - - Not Used - w/o HP2 TN 2501 High Speed GM LAN Serial Data (-) - HP2 15 - - Not Used 16 OG 640 Battery Positive Voltage

Conditions for Setting the DTCs

1. No valid messages are detected on the class 2 serial data circuit.
2. The voltage level detected on the class 2 serial data circuit is in one of the following conditions: High Low
3. The above conditions are met for approximately 3 seconds.

Action Taken When the DTCs Sets

The module uses default values for all parameters received on the class 2 serial data circuit.

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Retained Accessory Power (RAP) On After Timeout

Retained Accessory Power (RAP) On After Timeout

Retained Accessory Power (RAP) Inoperative

Retained Accessory Power (RAP) Inoperative

Control Module References

Control Module References

Data Link References

This table identifies which serial data link that a particular module uses for in-vehicle data transmission. Some modules may use more than one data link to communicate. This table is used to assist in correcting a communication malfunction between the control module and the scan tool. For the description and operation of these serial data communication circuits refer to Data Link Communications Description and Operation .

Data Link References

Scheme 14

Scheme 15

1. Disconnect the negative battery cables.
2. Remove the knee bolster. Refer to «Knee Bolster Replacement»(ref-238186-S18945448682006072400000) in Instrument Panel, Gages, and Console.
3. Disconnect the brown connector.
4. Disconnect all other connectors (1).
5. Remove the body control module (BCM) from the sliding bracket.

Programming the BCM

Perform the BCM special function "Request BCM Info. for SPS", then connect the scan tool to the SPS terminal and follow the instructions on the screen. Refer to Service Programming System (SPS) in Programming and Setup.

Programming Theft Deterrent System Components

Perform the Programming Theft Deterrent System Components in Theft Deterrent after successfully finishing the Setup New BCM procedure. If the Programming Theft Deterrent System Components in the Theft Deterrent procedure is not performed after a BCM replacement, one of the following conditions will occur

1. The vehicle will not be protected against theft by the PASSLOCK system.
2. The engine will not crank or start.

1. Turn the ignition OFF for 10 seconds.
2. Connect the scan tool to the data link connector.
3. Turn the ignition ON, with the engine OFF.
4. Use the scan tool in order to retrieve history DTCs from all modules.
5. Clear all history DTCs.

The data link connector (DLC) is a standardized 16 cavity connector. Connector design and location is dictated by an industry wide standard, and is required to provide the following

1. Scan tool power battery positive voltage at terminal 16
2. Scan tool power ground at terminal 4
3. Common signal ground at terminal 5
4. Class 2 signal at terminal 2
5. High speed GMLAN serial data bus (+) at terminal 6
6. High speed GMLAN serial data bus (-) at terminal 14

Class 2 Serial Data Line

Class 2 serial data is transmitted on a single wire at an average of 10.4 kbps. This value is an average, class 2 uses a variable pulse width modulation to carry data and depending on the message it may operate faster or slower. The bus will float at a nominal 7 volts during normal operation. Each module can pull this lower during the transmission. The bus is not at battery positive voltage or ground potential during normal operation. When the ignition switch is in RUN, each module communicating on the class 2 serial data line sends a state of health (SOH) message every 2 seconds to ensure that the module is operating properly. When a module stops communicating on the class 2 serial data line, for example if the module loses power or ground, the SOH message it normally sends on the data line every 2 seconds disappears. Other modules on the class 2 serial data line, which expect to receive that SOH message, detect its absence; those modules in turn set an internal DTC associated with the loss of SOH of the non-communicating module. The DTC is unique to the module which is not communicating, for example, when the inflatable restraint sensing and diagnostic module (SDM) SOH message disappears, several modules set DTC U1088. Note that a loss of serial data DTC does not normally represent a failure of the module that set it.

The class 2 serial data line on this vehicle is a star configuration. The powertrain control module (PCM) has an additional class 2 serial data circuit to body control module (BCM). If one of the class 2 serial data circuits to the PCM opens, communication will not be interrupted. The following modules communicate on the class 2 serial data line

1. The audio amplifier (AMP), w/UQ7 and Y91
2. The body control module (BCM)
3. The communication interface module (OnStar®), w/UE1
4. The digital radio receiver (DRR), w/U2K
5. The driver door module (DDM)
6. The electronic brake control module (EBCM)
7. The generator battery control module (GBCM)
8. The HVAC control module
9. The hybrid control module (HCM), w/HP2
10. The inflatable restraint sensing and diagnostic module (SDM)
11. The instrument panel cluster (IPC)
12. The memory seat module (MSM), w/AN3
13. The passenger door module (PDM)
14. The powertrain/engine control module (PCM/ECM)
15. The radio
16. The rear seat audio (RSA) controller, w/UK6
17. The rear seat entertainment (RSE) assembly w/U42
18. The rear wheel steering control module (RWSCM), w/NYS
19. The remote playback device - CD player (CDX), w/U1S
20. The transfer case shift control module (TCSCM), w/NP1/NP8
21. The transmission control module (TCM), w/M74

The class 2 serial data line allows a scan tool to communicate with these modules for testing purposes, checking for DTCs, and to activate/enable/disable functions. These class 2 serial data circuits are bussed together via 2 splice packs

1. SP205-Located behind the instrument panel (I/P) near the headlamp switch connector.
2. SP207-Located in the I/P harness.

Refer to Computer/Integrating Systems Component Views .

Controller Area Network (CAN) Serial Data Line w/6.6L Engine

The controller area network (CAN) serial data line does not communicate with the scan tool via the data link connector (DLC). CAN serial data information is interpreted by the modules that are on the class 2 also, and transmitted to the scan tool. The following modules communicate on the CAN serial data line

1. The engine control module (ECM)
2. The transmission control module (TCM)
3. The fuel injection control module (FICM)
4. The glow plug control module (GPCM)

The CAN serial data line, based on J1939 SAE standard, is high speed serial data bus used to communicate information among the modules. Typical data-transmission speeds must be high enough to ensure that the required real-time response is maintained.

The addressing scheme employed with CAN assigns a label to every message, with each message receiving a unique identifier. The identifier classifies the content of the message. Each module processes only those messages whose identifiers are stored in the module's acceptance list. This is CAN's form of message filtering.

The identifier labels both the data content and the priority of the message being sent. Each module can begin transmitting its most important data as soon as the bus is unoccupied. When more than one module starts to transmit simultaneously, the message with the highest priority is assigned first access. A module responds to failure to gain access by automatically switching to receive mode, the module then repeats the transmission attempt as soon as the bus is free again.

High Speed GMLAN Serial Data Line (PHT)

The data link connector (DLC) allows a scan tool to communicate with the high speed GMLAN serial data circuit through the CANdi module. The serial data is transmitted on two twisted wires that allow speed up to 500 Kbps. The twisted pair is terminated with two 120-ohm resistors, one is internal to the engine control module (ECM) and the other is internal to the energy storage control module (ESCM). The resistors are used to reduce noise on the high speed GMLAN bus during normal vehicle operation. The high speed GMLAN is a differential bus. The high speed GMLAN serial data bus (+) and high speed GMLAN serial data (-) are driven to opposite extremes from a rest or idle level. The idle level which is approximately 2.5 volts is considered a recessive transmitted data and is interpreted as a logic 1. Driving the lines to their extremes adds 1 volt to high speed GMLAN serial data bus (+) and subtracts 1 volt from high speed GMLAN serial data bus (-) wire. This dominant state is interpreted as a logic 0. GMLAN network management supports selective start up and is based on virtual networks. A virtual network is a collection of signals started in response to a vehicle event. The starting of a virtual network signifies that a particular aspect of the vehicles's functionality has been requested. A virtual network is supported by virtual devices which represents a collection of signals owned by a single physical device. So, any physical device can have one or more virtual devices. The signal supervision is the process of determining whether an expected signal is being received or not. Failsofting is the ability to substitute a signal with a default value or a default algorithm, in the absence of a valid signal. Some messages are also interpreted as a "heartbeat" of a virtual device. If such a signal is lost, the application will set a no communication code against the respective virtual device. This code is mapped as a code against the physical device. Note that a loss of serial data DTC does not normally represent a failure of the module that set it.

The powertrain control module (PCM) and hybrid control module (HCM) are functionally communicating on both class 2 and high speed GMLAN data links. However the diagnostic communication of the above modules with the scan tool is performed on class 2 data link only. All DTCs set by the high speed GMLAN modules, including HCM, are reported by the PCM on class 2. Data displaying, output controls and programming of the control modules connected to high speed GMLAN only, is performed through high speed GMLAN link.

The GMLAN serial data communications circuit is in a linear topology. The following modules are connected to the link, in order from DLC to the end of the linear configuration

1. The energy storage control module (ESCM)
2. The starter/generator control module (SGCM)
3. The electro-hydraulic power steering (EHPS)
4. The hybrid control module (HCM)
5. The powertrain control module (PCM)

BCM Functions

The body control module (BCM) performs multiple body control functions. The BCM can control devices directly connected to its outputs based on input information. The BCM evaluates this information and controls certain body control systems by commanding outputs on or off. The BCM control inputs can be

1. Sensors and switches that are directly connected to the BCM
2. Class 2 serial data received from other control modules connected to the class 2 serial data link.

The BCM is also capable of controlling other vehicle systems that are not directly wired to the BCM. The BCM does this by sending specific messages on the class 2 serial data link. The control module capable of performing the required function will respond to the BCM message.

The BCM controls these functions

1. Audible warnings, refer to «Audible Warnings Description and Operation»(ref-238186-S10075706942006072400000) in Instrument Panel, Gages and Console
2. Automatic door locks, refer to «Power Door Locks Description and Operation»(ref-238183-S19982706062006072400000) in Doors
3. Automatic headlamp control, refer to «Exterior Lighting Systems Description and Operation»(ref-238182-S28312914802006072400000) in Lighting Systems
4. Interior lighting, refer to «Interior Lighting Systems Description and Operation»(ref-238182-S14213871632006072400000) in Lighting Systems
5. Keyless entry (AUO option), refer to «Keyless Entry System Description and Operation»(ref-238201-S35003528892006072400000) in Keyless Entry.
6. Passlock theft deterrent, refer to «Vehicle Theft Deterrent (VTD) Description and Operation»(ref-238205-S42466208142006072400000) in Theft Deterrent.
7. Retained Accessory Power (RAP), refer to «Retained Accessory Power (RAP) Description and Operation»(ref-238179-S30668707092006072400000)

Power Mode

The BCM is the power mode master (PMM). Refer to Power Mode Description and Operation for more information.

Serial Data Power Mode

On vehicles that have several control modules connected by serial data circuits, one module is the power mode master (PMM). On this vehicle the PMM is the body control module (BCM). The BCM uses 3 signals from the ignition switch. These are the Ignition 0, Ignition 1, and Accessory.

To determine the correct power mode the BCM uses

1. The state of these signals
2. The sequence of switch closures received by the BCM
3. The status of the engine run flag

The chart indicates the power modes detected and transmitted by the BCM

Correct Ignition Switch Inputs

Serial Data Messages

The modules that depend exclusively on serial data messages for power modes stay in the state dictated by the last valid BCM message until they receive the engine status from the powertrain control module (PCM). If the BCM fails, the modules monitor the serial data circuit for the engine run flag serial data. If the engine run flag serial data is true, indicating that the engine is running, the modules fail-safe to Run. In this state the modules and their subsystems can support all operator requirements. If the engine run flag serial data is false, indicating that the engine is not running, the modules fail-safe to OFF-AWAKE. In this state the modules are constantly checking for a change status message on the serial data circuits and can respond to both local inputs and serial data inputs from other modules on the vehicle.

Discrete Ignition Signals

Those modules that have discrete ignition signal inputs also remain in the state dictated by the last valid BCM message received on the serial data circuits. They then check the state of their discrete ignition input to determine the current valid state. If the discrete ignition input is active, B+, the modules will fail-safe to the RUN power mode. If the discrete ignition input is not active, open or 0 voltage, the modules will fail-safe to OFF-AWAKE. In this state the modules are constantly checking for a change status message on the serial data circuits and can respond to both local inputs and serial data inputs from other modules on the vehicle.

Serial Data Control of Retained Accessory Power (RAP)

The class 2 modules receive the power mode message from the body control module (BCM) over the serial data circuits, indicating when the retained accessory power (RAP) power mode is current. The BCM monitors the ignition switch position, battery condition and passenger compartment doors status to determine whether RAP should be initiated. The modules then support the operation of the systems under their control as required by their RAP power mode operation.

RAP will end when one of the following conditions is met

1. The BCM receives an input indicating the opening of any compartment door.
2. The BCM internal timer for the RAP expires after approximately 10 minutes.
3. The BCM detects a decrease in battery capacity below a prescribed limit.

The BCM then sends a serial data power mode message Off-Awake ending the RAP function.

The class 2 RAP functions are

1. The power windows
2. The radio